As actuators, especially so-called pump-nozzle units are used, in which the pressure buildup and the control of the injected fuel quantity take place in a structural unit, or pump-line-nozzle systems are used. Correspondingly, as actuator, an injector may also be used to which the fuel is supplied under high pressure, and the injector merely controls the fuel metering.
Usually such actuators are encumbered with tolerances. This means that, for the same control signal, different injectors meter in different fuel quantities. Furthermore, tolerances are able to have the effect that, in response to the same operating conditions, for the same control signal, different fuel quantities are metered in.